The present invention relates to systems and methods for separating hydrophobic fluids (such as oils) which are entrained as aerosols, from gas streams (for example, air streams). Preferred arrangements also provide for filtration of other fine contaminants, for example carbon material, from the gas streams. Methods for conducting the separations are also provided.
Certain gas streams, such as blow-by gases from diesel engines, carry substantial amounts of entrained oils therein, as aerosol. The majority of the oil droplets within the aerosol are generally within the size of 0.1-5.0 microns.
In addition, such gas streams also carry substantial amounts of fine contaminant, such as carbon contaminants. Such contaminants generally have an average particle size of about 0.5-3.0 microns.
In some systems, it is desirable to vent such gases to the atmosphere. In general, it is preferred that before the gases are vented to the atmosphere, they be cleaned of a substantial portion of the aerosol and/or organic particulate contaminants therein.
In other instances, it is desirable to direct the air or gas stream into equipment. When such is the case, it may be desirable to separate aerosol and/or particulates from the stream during the circulation, in order to provide such benefits as: reduced negative effects on the downstream equipment; improved efficiency; recapture of otherwise lost oils; and/or to address environmental concerns.
A variety of efforts have been directed to the above types of concerns. The variables toward which improvements are desired generally concern the following: (a) size/efficiency concerns; that is, a desire for good efficiency of separation while at the same time avoidance of a requirement for a large separator system; (b) cost/efficiency; that is, a desire for good or high efficiency without the requirement of substantially expensive systems; (c) versatility; that is, development of systems that can be adapted for a wide variety of applications and uses, without significant re-engineering; and, (d) cleanability/regeneratability; that is, development of systems which can be readily cleaned (or regenerated) if such becomes desired, after prolonged use.
An arrangement for separating a hydrophobic liquid phase from a gaseous stream comprises a coalescer filter, a housing construction, a gas flow direction arrangement, and a liquid collection arrangement. The coalescer filter preferably comprises a non-woven media of fibers. The housing construction defines an interior and has a gas flow inlet and a gas flow outlet. The gas flow direction arrangement is constructed and arranged to direct gas flow (for example crankcase blow-by gas flow) through the coalescer filter as the gas is directed into and through the housing construction. The liquid collection arrangement is positioned within the housing construction and is oriented for receiving liquid collected within the coalescer filter and drained therefrom.
Preferably, the coalescer filter comprises a panel construction removable from, and replaceable in, the arrangement.
Preferably, a liquid drain construction is in fluid communication with the liquid collection arrangement. The liquid drain construction is constructed and arranged to selectively drain collected hydrophobic liquid from the housing construction interior.
In certain preferred embodiments, the arrangement further includes a second filter. Preferably, the second filter is positioned within the housing construction and is located downstream from the coalescer filter. The gas flow direction arrangement is constructed and arranged to first direct gas flow through the coalescer filter and then to secondly direct gas flow through the second filter, as gas is directed into and through the housing construction.
Preferably, the coalescer filter has an upstream surface area of no more than 25% of an upstream surface area of the second filter. In certain preferred embodiments, the coalescer filter has an upstream surface area of about 0.1%-10%, typically about 0.5-1% and preferably about 0.8%, of an upstream surface area of the second filter.
Preferably, the second filter comprises pleated media. In certain arrangements, the second filter is removable and replaceable, and the housing is constructed and arranged with an openable end cover for access to remove the second filter without removal or dismounting of the coalescer filter. The first and second filters can be mechanically connected to be replaced as one unit; or, they can be separate constructions to be replaced separately.
In one preferred embodiment, the coalescer filter comprises a non-woven media of fibers having an average fiber diameter of less than 25 microns, typically and preferably within the range of 9-25 microns.